A major concern in the clinical application of tumor necrosis factor related apoptosisâinducing ligand (TRAIL) in tumors is the development of resistance. Therefore, agents that can potentially restore TRAIL sensitivity are important therapeutic targets for cancer treatment. Herein, we evaluated lanatoside c and digoxin, both of which are widely used cardiac glycosides (CGs), for their ability to sensitize human hepatocellular carcinoma cells (Huhâ7 and HepG2) through TRAILâinduced apoptosis. CGs functionalize TRAIL as shown by its effect on intracellular reactive oxygen species (ROS) generation, which damages mitochondrial integrity and thereby confers intrinsic apoptotic caspase cascade during combined treatment. Caspase activation is dependent on ROS as shown by the ability of CGs to generate ROS and the ROSâNâacetylcysteine (NAC) relationship, which inhibits apoptosis during cotreatment by preventing the formation of caspaseâ8 and â3. Furthermore, CGs triggered p38MAPK phosphorylation and NAC preâexposure blocked p38MAPK phosphorylation, which demonstrated that p38MAPK was dependent upon ROS generation. Additionally, CGs were found to be potent inducers of AMPKâmediated protective autophagy as pharmacological and genetic autophagy inhibition reached the higher threshold of TRAILâmediated apoptosis. Finally, CGs downregulated the expression of the antiapoptotic protein Bclâ2 and increased the translocation of proapoptotic protein cytochrome c, thereby inducing apoptosis. Collectively, these results indicate that CGs potentiate the enhanced cytotoxic capacity to TRAIL through ROS generation, p38MAPK phosphorylation, cell survival protein downregulation, and protective autophagy inhibition.